From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45075) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yssdj-0006BR-Nv for qemu-devel@nongnu.org; Thu, 14 May 2015 08:53:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yssdg-0006uI-FN for qemu-devel@nongnu.org; Thu, 14 May 2015 08:53:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38020) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yssdg-0006tt-Ac for qemu-devel@nongnu.org; Thu, 14 May 2015 08:53:24 -0400 Message-ID: <55549ABD.2050202@redhat.com> Date: Thu, 14 May 2015 14:53:17 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <20150513174204.GS23627@redhat.com> <5553C651.4060000@redhat.com> <20150514111825.GE3441@redhat.com> <878ucr4bb7.fsf@blackfin.pond.sub.org> <555490EE.1040802@redhat.com> <87egmjz5sl.fsf@blackfin.pond.sub.org> In-Reply-To: <87egmjz5sl.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Kevin Wolf , xen-devel@lists.xensource.com, Stefano Stabellini , mst@redhat.com, qemu-devel@nongnu.org, John Snow , rth@twiddle.net On 14/05/2015 14:45, Markus Armbruster wrote: > Paolo Bonzini writes: >=20 >> On 14/05/2015 14:02, Markus Armbruster wrote: >>> It should certainly be off for pc-q35-2.4 and newer. Real Q35 boar= ds >>> commonly don't have an FDC (depends on the Super I/O chip used). >>> >>> We may want to keep it off for pc-i440fx-2.4 and newer. I doubt >>> there's a real i440FX without an FDC, but our virtual i440FX is qui= te >>> unlike a real one in other ways already. >> >> That would break libvirt for people upgrading from 2.3 to 2.4. So it'= s >> more like pc-i440fx-3.0 and pc-q35-3.0. >=20 > What exactly breaks when? libvirt expects "-nodefaults -drive if=3Dnone,id=3Dfdd0,... -global isa-fdc.driveA=3Dfdd0" to result in a machine with a working FDD. It doesn't know that it has to add "-machine fdc=3Don". Besides, adding a new machine option is not the best we can do. If the default is "no FDC", all that is needed to add one back is -device. An FDC is yet another ISA device, it is possible to create one with -device. > add the magic to make -global isa-fdc... auto-set the option to on. That would be ugly magic. The more I think about this, the more I think this is just a kneejerk reaction to a sensationalist announcement. The effect of this vulnerability on properly configured data centers (running non-prehistoric versions of Xen or KVM and using stubdom/SELinux/AppArmor properly) should be really close to zero. It's a storm in a tea cup. Paolo >> Unless for q35 we decide to >> break everything and retroactively nuke the controller. >> >> (I'm still not sure why we have backwards-compatible machine types for= q35). >=20 > Beats me :) >=20 > [...] >=20